In fabricating products from continuous lengths of at least partially thermoplastic material, it is often necessary to cut off predetermined amounts of undesirable material from each longitudinal side edge portion of the material. This is particularly true when the material is textile fabric having at least some thermoplastic fibers and woven on air jet looms or the like which produce fringed selvages along the longitudinal side edges which are not desirable in the fabricated end products, such as bed sheets, piece goods or the like, as more fully set forth in copending application Ser. No. 555,664, filed Nov. 28, 1983, and assigned to the assignee of the present sent application, the disclosure of which is incorporated herein by reference.
As set forth in the aforementioned, copending application, various types of apparatuses were investigated by assignee for cutting off predetermined widths of undesirable material or selvage and sealing the cut edges to produce an aesthetically pleasing cut and sealed edge, which in the case of bed sheets, piece goods or the like, required a wash durability of at least 25 to 50 washings without significant raveling of the yarns at the cut and sealed edges. As a result of these investigations, ultrasonic apparatus was chosen as being the most promising for accomplishing the above. However, for the most part, such ultrasonic apparatus had been primarily commercially utilized with all plastic or thermoplastic sheet materials. Notwithstanding, such ultrasonic apparatus had been proposed for cutting and edge sealing textile fabrics having at least some thermoplastic yarns therein and is advantageous for a number of reasons as compared to other types of operations, including cutting and hemming operations.
As a result of experimentation with commercially available ultrasonic apparatus, it was determined that the construction of such ultrasonic apparatus did not satisfactorily cut clean and sharp edges along the material, while providing desired amounts of edge sealing in the material and while resisting wear on the anvil. Specifically, it was found with the use of this commercially available ultrasonic cutting and sealing apparatus, that, if a particular commercially available anvil construction was utilized which provided a clean and sharp cut along the edge of the material, then a desired amount of edge sealing inwardly of the cut edge was not obtained and the anvil would wear and not perform satisfactorily after a short period of use. On the other hand, it was found that if a commercially available anvil construction was utilized which produced a desired amount of edge sealing inwardly of the ultrasonically cut edges, then a clean and sharp cut was not obtained along the edges of the material. Other problems with such commercially available ultrasonic apparatus are set forth in the aforementioned copending application.